It is well understood that the greater the vaporization or gasification of liquid fuel that can be accomplished the greater the surface area of the fuel which is subject to oxidation and therefore the higher the rate of combustion. Many individuals working in the field felt that if complete conversion of the fuel to the gaseous state could be accomplished, a highly efficient clean operating engine could be provided. Attempts to completely gasify liquid hydrocarbon fuel go back many years. However, all of these attempts have had significant shortcomings. In some instances, the devices did not completely vaporize the fuel and therefore the expected increase in efficiency did not materialize. In other cases, the devices were of such a complex nature as to negate any real benefit from them or require such high power inputs themselves that even though a greater fuel efficiency was realized, the increased power needs negated this benefit. The complete conversion of fuel to vapor created another unexpected problem. Although the fuel would rapidly and completely burn, it was discovered that the expansion of the fuel in forming a gas occurred too early. Therefore, the density of the fuel, when mixed with air was so low that not enough fuel could be directed into the combustion chambers of the engine to generate power equal to other state of the art devices such as carburetors, throttle body injection systems or direct port injection systems.
One of the most noted prior art devices which was developed by Charles Nelson Pogue in the 1930s was a carburetor for the vaporization of gasoline which has been widely advertised as the "two hundred mile per gallon carburetor". This device has never enjoyed wide commercial success because it is nearly as large and cumbersome as the engine it is meant to fuel and it requires an operating temperature which approaches the flash point of the fuel, such as gasoline, so that the potential for an explosion is quite great.
A device for vaporizing fuel, such as diesel fuel is disclosed in U.S. Pat. No. 1,806,581 to Bethenod for "Fuel Supply System For Internal Combustion Engines of Variable Load For Using Heavy Fuels". The diesel fuel is supplied through a conventional gasoline carburetor and air is drawn through an intake by means of a vacuum pump. This system is an open system, i.e., air in large quantities is continuously drawn in from the atmosphere by a first vacuum pump. A second vacuum pump is intended to pull a vacuum on the air-fuel mixture in a reservoir to vaporize the fuel whereupon it is fed into a manifold of an engine which is supplied with still an additional air intake. Heat exchange means are provided around the reservoir and again near the intake manifold to minimize fluctuations in fuel temperature. Because the system is open, large quantities of air are drawn through it making it very difficult to draw a sufficient vacuum to substantially vaporize any fuel which is not vaporized directly by the carburetor. In other words, for such a device to operate effectively it would be necessary to provide such a huge vacuum pump that the fuel savings, if any, would be negligible. Alternatively, with a smaller vacuum pump the fuel is not properly vaporized in an open system because atmospheric air is constantly being drawn into the system.
Another device for providing gaseous fuel to the carburetor of an internal combustion engine is shown in U.S. Pat. No. 3,630,698 to Joseph H. Baldwin for "Fuel System". In this device, gaseous vapors are drawn from a vacuum chamber by means of a manifold vacuum. The vacuum chamber contains a supply of liquid fuel which is replenished through a float valve. Two potential problems are associated with this type of device. First, the vacuum from the manifold may not be sufficient under certain load conditions to provide sufficient fuel to the engine. Second, by drawing the gaseous vapors off of a body of liquid gasoline the lighter hydrocarbons are boiled off first, leaving a relatively heavy liquid hydrocarbon, frequently referred to as "strip oil". Therefore, in order to keep them working properly, means must be provided to regularly withdraw the strip oil and replace it with fresh gasoline.
Another device for vaporizing gasoline is disclosed in Rose, et al. U.S. Pat. No. 4,040,403 for "Air Fuel Mixture Control System". In this device, fuel is supplied to a vaporizer wherein the level of the liquid fuel in the vaporizer is controlled by a float valve. Hot exhaust gases from the engine are boiled through the liquid gasoline causing a portion of it to be vaporized and carried to the engine. The device includes a complex amplifying system for adjusting the air-fuel mixture and a separator for taking out any fuel droplets from the fuel as it is vaporized in the vaporizer. With this device, the lighter hydrocarbons will be vaporized leaving behind the heavier hydrcarbons or strip oil.
Johnson U.S. Pat. No. 4,175,525 for "Fuel Vaporizer System For Internal Combustion Engines" discloses a sealed vaporization system connected between a fuel supply line and the intake manifold of an internal combustion engine and operated in parallel with a carburetor. A float valve is provided in this device to control the flow of liquid fuel to a chamber wherein it is vaporized and fed to a carburetor. The lighter hydrocarbons will be boiled off the liquid fuel before the heavier hydrocarbons, leaving strip oil in the chamber.
Additional devices for vaporizing fuel are disclosed in James E. Gilmor U.S. Pat. No. 4,483,305 for "Fuel Vaporization Device" and James E. Gilmor U.S. Pat. No. 4,483,307 for "Fuel Vaporization Device For Internal Combustion Engine". These devices are designed to instantaneously vaporize all of the fuel.
Meier et al. U.S. Pat. No. 4,522,183 for "Method For Converting a Retrograde Substance to the Gaseous State" is directed to a method wherein the fuel is prepressurized and heated and the pressure released for abruptly converting a retrograde fuel to a gaseous state. While the method may be effective to accomplish its intended result, it is not believed that sufficient fuel can be provided to an internal combustion engine by the practice of this method to operate it satisfactorily, particularly under load.
The ultimate carburetion system would be one in which a small percentage of the fuel is vaporized and the rest of the fuel is converted to microscopic liquid fuel droplets prior to introducing the fuel into the intake manifold of an internal combustion engine. When mixed with air in the manifold the vaporized fuel and the microscopic fuel droplets disperse with some additional vaporization.
For convenience, gaseous fuel will be referred to as "vapor" or "vaporized fuel"; liquid fuel droplets of a size not visible with the naked eye, under normal lighting conditions, will be referred to as "microscopic" particles or droplets and liquid fuel droplets of a size which is visible with the naked eye will be referred to as "macroscopic" droplets. Ideally, macroscopic liquid fuel droplets from a suitable source, such as one or more fuel injectors, are converted to a mixture consisting of a small percentage of fuel vapor and a large percentage of microscopic fuel droplets. This mixture will be referred to as "converted fuel".